Pow, Bang, Sizzle - It was bound to happen! :

[electronrancher]

Well, I finally blew something up. I should be feeling remorseful but I work on IC's for a living and I know very well the first two rules of IC's.

1) Every chip actually runs on smoke, not silicon.
2) In every chip there is a secret function that allows the user access to this smoke, you just have to find it!

Now I need some help - what's the power amp used in the audio circuit of a rodeo? It's a 12-pin SIP (single inline pins) with a big ass heat sink. My part number is LA4xx1 I think. The xx's are obscured by a huge crater blown out of the front of the chip, and the 4 is half gone so I'm only guessing here.

I wasn't even meddling, I just switched the volume slider switch while audio was playing and pow - she was gone. I'll replace it, but boy is that chip a piece of crap or what? No protection mechanisms on that bad boy? Damn, my chips have to have undervoltage lockout, overvoltage fault, current limit, overcurrent fault, and over temperature protection - was this chip made in 1971 or something? (Actually from some other LA4xxx datasheets I see, the chip was circa 1997 but it looks truly stone-age)

Anyway, if you have a rodeo, or another machine that uses an LA???? 12-pin audio power amp, please post the part number.. Thanks!!

[musky]

Well, I looked in my Jet Set Radio but was unable to ind a chip of that type. Sorry

[slotter]

How about a picture of the chip and where it is located in the machine. That would sure help identifying what you are dealing with...

[electronrancher]

Ok here are the pics. first one is the board, and second one is a closeup of the chip so you can admire the crater. The dead chip is the one attached to the heatsink.. Part number looks like a LA4xx2, not 4xx1 - my mistake.

[cmk8895]

Hmmm And you can't find the chunk inside the machine anywhere? It could be a fun little puzzle to put the pieces back together.

I guess I didn't know chips could explode these days. I figured that was all in the past. Live and learn I guess.

cmk

[electronrancher]

I think the amplifier is made with bipolar transistors, which do a really neat thing called thermal runaway. When a part of the chip gets hot, the transistors get stronger - naturally, they begin to pump more current with their newfound strength which only makes them hotter. So on and so forth, until a giant smoking crater is formed.

Usually there are some sort of protections in place to prevent the addition of this crater, but apparently not on this chip. Judging by how many complaints I heard about burning your amp when trying to add a volume knob, I thought this would have been an easy one to find a replacement for.

[rupan777]

It's threads like these that make me wish I had paid more attention during Electronics 100 class in high school.

[azlew]

It's threads like these that make me wish I had paid more attention during Electronics 100 class in high school.

Yeah me also. I wouldn't attempt any of this stuff myself. But a simple plug in 50 credit autocredit mod would be tempting if all I had to do was plug in one wire(no soldering )

[cmk8895]

if all I had to do was plug in one wire(no soldering )

wuss!

heheh

cmk

[Sid]

Hey a little electricity never hurt noone.. ..
bzzzzzzzzzzzzzzzzzzzzzzttttttttttt.........

[azlew]

wuss!

heheh

cmk

Yep : I get scared just changing a light bulb in a lamp

[electronrancher]

If you can find the connectors, I'll build a plug-in mod for you.

[electronrancher]

I found a chip which *could* be the right one. I would still like confirmation if anone has a board like this. My sound/video board shown above was mounted to the top left of the door, right behind the LCD panel. It was housed in a security sealed plastic shell, for reasons I couldn't begin to guess at.


Ha - and they're only 3 bucks! I shoulda blown this thing up a long time ago!

[cmk8895]

You could go through a searchable product finder. Put in the mask of the chip number which would get you down to 100 possible chips, probably less since all of them won't be valid numbers. Then search for which ones come in the right package and have the correct number of pins. I'd bet there are only a couple left by that point.

The one you found looks good, though. It makes a lot of sense for a chip on a sound board.

cmk

[alstonj1]

pardon the pun but , NICE HOLE IN ONE!!!!! and its not smoke its sparks that you set free !!!! sorta like free willy ........ did the same thing with a u.s. slot machine i just picked up this weekend it had no keys and someone had laid it on its back and dumped the tokens inside (a few lucky ones made their home in the power supply ) when i plugged it in and turned it on there was a spark reunion going on down below till the murphy's law guys came in and blew the main fuse on the power supply now i gotta resurect the power supply from the ashes ........

[d mowery]

Reminds me of the time ,I drove 2 nails throu a board bout 4 inchs apart and hooked a elec cord to them and put hot dogs on them ,man you could see them suckers fry from the end to the middle , had a good thing going till one of the over edjamcated techs tried to take one of with a fork BEFORE unplugging , Bet he never does that any more ,needless to say the dog fryer went in the trash after that , Man I miss that cooker

[alstonj1]

heres's a few pics of the twins i just got named em peter and paul .... robbing peter to fix paul right now . pauls 100% now and peters damage was only the afore mentioned power supply so far should have it up and running soon . these are the american cousins to my pachi's and as usual there a hell of a sight bigger and weigh in at around 170 lbs or so but are authentic vegas slots set up for skillstop but will take what ever i set em up for they have a coin compariator not a coin mech so you put in a sample coin and tweak it in and thats what it only accepts. Will probably sell one of them when i get the second one up and running.......

[slotter]

Very interesting! Thanks!

[electronrancher]

Is that an S+? Boy do I ever want to buy one of those - cool!!!

[cmk8895]

I've been looking for a "real" slot machine myself. The other half isn't biting off on the pachislo bug. What's wrong with some people anyway?

cmk